python - Raspberry ALSA 声音输出/输入从机

Question

我正在尝试将一台设备设置为播放，将另一台设备设置为捕获，我的 nano/etc/asound.conf 有这个:

pcm.!default {
        type asym
        playback.pcm "plughw:1,1"
        capture.pcm  "plughw:1,0"
}

ctl.!default {
        type hw
        card 0
}

我可以完美地播放声音，但我无法录制声音，我的 python 代码抛出此错误:

ALSA lib pcm_dmix.c:1018:(snd_pcm_dmix_open) 
unable to open slave
ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side

ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) 
Unknown PCM cards.pcm.hdmi
ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.hdmi
ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.modem
ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.modem
ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.phoneline
ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.phoneline

ALSA lib pcm_dmix.c:957:(snd_pcm_dmix_open) 
The dmix plugin supports only playback stream

ALSA lib pcm_dmix.c:1018:(snd_pcm_dmix_open) 
unable to open slave

这是我正在运行的代码的一部分:

import pyaudio
class Microphone(AudioSource):
    def __init__(self, device_index = None):
        self.device_index = device_index
        self.format = pyaudio.paInt16 # 16-bit int sampling
        self.SAMPLE_WIDTH = pyaudio.get_sample_size(self.format)
        self.RATE = 16000 # sampling rate in Hertz
        self.CHANNELS = 1 # mono audio
        self.CHUNK = 1024 # number of frames stored in each buffer

        self.audio = None
        self.stream = None

    def __enter__(self):
        self.audio = pyaudio.PyAudio()
        self.stream = self.audio.open(
            input_device_index = self.device_index,
            format = self.format, rate = self.RATE, channels = self.CHANNELS, frames_per_buffer = self.CHUNK,
            input = True, # stream is an input stream
        )
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        self.stream.stop_stream()
        self.stream.close()
        self.stream = None
        self.audio.terminate()

我该如何解决这个错误？

提前谢谢你。

Answer 1

pyaudio 基于 PortAudio ;所有这些愚蠢的消息都是因为 PortAudio 试图枚举音频设备。

pyaudio 设备索引不一定与 ALSA 卡索引相同。使用 get_device_count()和 get_device_info_by_index()找到要使用的输入设备。